L.TileLayer.Kitten = L.TileLayer.extend({
    getTileUrl(coords) {
        var i = Math.ceil(Math.random() * 4);
        console.log('coords:', coords, i);
        // return 'https://placekitten.com/256/256/?image=' + i;
        return i + '.jpg';
    },

    getAttribution() {
        return "<a href='https://placekitten.com/attribution.html'>PlaceKitten</a>";
    },
});

L.tileLayer.kitten = function () {
    return new L.TileLayer.Kitten();
};
